Potencial antimicrobiano de extratos de café na inibição de bactérias gram-positivas e gram-negativas
lant extracts ingredients as coffee have the characteristic of being natural, safe,andhealthy, mainly due itsantioxidant activityensured by the presence of bioactive compounds as chlorogenic acids, caffeine,and melanoidins, which mayalso have antibacterial activity. The objective of t...
| Autor principal: | Canci, Luiza Andréa |
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| Formato: | Dissertação |
| Idioma: | Português |
| Publicado em: |
Universidade Tecnológica Federal do Paraná
2020
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.utfpr.edu.br/jspui/handle/1/5258 |
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| Resumo: |
lant extracts ingredients as coffee have the characteristic of being natural, safe,andhealthy, mainly due itsantioxidant activityensured by the presence of bioactive compounds as chlorogenic acids, caffeine,and melanoidins, which mayalso have antibacterial activity. The objective of this study was to evaluate the antibacterial effect of arabica roasted (Coffea arabica) extracts (AT), robusta roasted (Coffea canephora) coffee (CT) and robusta green (Coffea canephora) coffee(CV) against SalmonellaTyphimurium, Escherichia coli, Staphylococcus aureus, Lactobacillus plantarum,and Lactobacillus rhamnosus. Initially, the determinationof melanoidins, caffeine,and chlorogenic acids was performed in the coffee extracts mentioned. For the initial screening of the coffee extract inhibitory effect bacterial sensitivity was assessedby the evaluation sterile discs impregnation with coffee extracts in concentrations of 0.5;1.5;2.0;2.5;and 5.0% (mv-1), which were deposited in specific solid media inoculated with the target microorganisms; the inhibitory effect wasevaluated at zeroand twenty days of storage under refrigeration. As a positive control, disks containing antibiotics for commercial use asAmoxicillin clavulanic acid and Trimetoprim (5 μg),and Ampicillin (10 μg). Salmonella Typhimurium, Escherichia coli and Staphylococcus aureus showedcoffee extract sensitive,andthree concentrations (0.5%, 2.5%,and 5.0%) were selected for cell growth monitoring in liquid medium. The tests were evaluated by optical density reading at 600 nm, at predefined intervals of 1 hand the data obtained were adjusted to the modified Gompertz mathematical model (MGM),in order toobtain the growth parameters of lagphase duration maximum specific growth rate (μ),and logarithmic increase in the population (A). Among coffee extracts, 5.0% CT showed the best performance in antibacterial activity reduction for SalmonellaTyphimurium (1.3 log cycle), forEscherichia coli (1.4 log cycle),and for Staphylococcus aureus (1.5 log cycle). The coffee extract CT presentedthe highest content of melanoidins compared to others, indicating that the inhibitory biological activity may be associated with the presence of these compounds in the evaluated extracts.Moreover, the CTextract was used to evaluate the antibacterial performance in food matrix (reconstituted skimmed-milk powder) bythe addition of 5.0% and inoculated with 0.1%(v/v) (initial count of 105UFC mL-¹) ofSalmonellaTyphimurium, Escherichia coli, Staphylococcus aureus, Lactobacillus rhamnosus,and Lactobacillus plantarum, with a sample incubated at 5 °Cand another at 35°C, for each microorganism. Microbial growth was monitored every 12 h, by inoculation in suitable solid media for each microorganism, up to 72 h. The results were adjusted to the modified Gompertz model (MGM), obtaining the parameters of μ and A. It was possible to observe the antimicrobial effect of the coffee extract CT without interference from the food matrix, with the reduction of the logarithmic increase in the population(A) for Salmonella, Escherichia coli, and Staphylococcus aureus. For Salmonellaand Escherichia coli, there was a decrease in the maximum specific growth rate (μ) in the temperature of 5°C, and a reduction of 1.12 and 1.58 log cycle, respectively;however, at 35 °Cthe microorganismsreduction was lower, 0.29 and 0.62 log cycle ifcompared to controls. For Staphylococcus aureus, at temperatures of 5 °C and 35 °C, a reduction in the logarithmic increase in the population of 1.72 and 2.83 log cycle was observed, respectively, values justified by the decrease in the maximum specific growth rate. For Lactobacillus rhamnosus andLactobacillus plantarum there was no growth inhibition in the food matrix with 5.0% CT coffee extract, atthe temperatures evaluated. It is concluded that the 5.0% concentration of robusta roasted coffee (CT) demonstrated success in inhibiting the pathogens SalmonellaTyphimurium, Escherichia coli, and Staphylococcus aureus grown in liquid medium and food matrixreconstituted powdered milk. However, this coffee extract (CT at 5.0%), did not show inhibitory activity against Lactobacillus rhamnosus and Lactobacillus plantarum in theinitial agar sensitivity and in the milk powder matrixtests, demonstrating to be applicable in matrices containing these probiotics. |
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